I think you want to prove that a rectangle is a quadrilateral. You can prove this with definitions. The definition of a quadrilateral is that it is a shape with four sides. Since a rectangle has four sides, that proves that a rectangle is a quadrilateral.
There are a few criterias... One angle is a right angle Two pairs of opposite sides that are congruent Congruent diagonals Opposite sides are parallel...
Hope this helps please give me a 5-rate, thanks, and brainliest!
